Step three and a half : Messing around

I wasn't sure if the properties of "Tree" became sub properties of the
tree entity - looks like component functions are kind of inherited. So
if I was to add "color" to tree again maybe it would override or
interfer with the previous color.
`
Some more fiddling around with components

OK so it seems like the attributes are left-right applied. So if you
define entity as having components 'tree, bush', the attributes of bush
get applied.

Wonder if in more complex graphs this gets sticky.